[Neonatal infection and high IgM at birth].

To determine the concentration of IgM to be used as intrauterine infection indicator, the sera of 2,906 newborns were studied. Five hundred and sixty-three (19.4%), showed high concentrations of IgM and out of 199 pair sera studied, serologic evidence of infection was found in 21.1%. Out of these cases, 80.9% showed no clinical disturbances during their first two months of life. The agents most frequently found responsible for intrauterine infection were cytomegalovirus, influenza A2 H-K, influenza B, parotiditis and rubella. Based on this study, we may conclude that determinations of high concentrations of IgM with the technique used is still a good index to detect intrauterine infections, specially considering that the clinical manifestations of disease may be minimal or may pass unnoticed during the first days of life and that by no means should this test be done instead of other clinical or laboratory studies to investigate such questions.